How to import and export blender files with textures
PROBLEM SOLVED!

This is how I did it:


Make sure the object to be exported (plant) is selected in object mode
File: Export: 3ds
I opened the scene (room.blend)
Select A twice to make sure everything is deselected
File: Import: 3ds
The object (plant) is grey
With the object selected switch to edit mode
Deselect everything again by pressing A
Hover your mouse over the parts you have created individually and press L
The selected part will be highlighted (ex. leaf)
Go to Material (On the right side of the screen)
A list of the original materials is there but they are all blank
Select the corresponding material (ex: leaf)
Go to Use Nodes/Color and select the dark grey area on the right indicated by a circle
A menu will appear: select Image Texture
Open the file with the UV map you created (ex:UV_MAP_leaf)
For colors without the UV map, I had to recreate them (ex: pot, dish)


Repeat these steps with every single part in the object and that's it!